Electro-magnetic cut-off



(No Model.)

E. THOMSON.

ELEGTRO MAGNETIC GUT-OFF. No. 360,123. Patented Mar. 29, 1887.

WITNESSES INVENTOR Q (12% 7M fwd @Mfi ATTORNEY UNITED STATES PATENTOFFICE...

ELIHU THOMSON, OF LYNN, MASSACHUSETTS.

ELECTRO-MAGNETIC CUT-OFF.

SPECIFICATION forming part of Letters Patent No. 360,123, dated March29, 1887.

Application filed August 25, 1886. Serial No. 211,857.

To all whomit may concern.-

Be it known that I, ELIHU THOMSON, a citizen of the United States, and aresident of Lynn in the county of Essex and State of Massachusetts, haveinvented a certain new and useful Electro-Magnetic OutOff Mechanism, ofwhich the following is a specification.

The present invention relates to means for establishing and preservingthe continuity of an electric circuit-such as an arc-light line or otherconstant-current lineupon which incandescent lamps or other translatorsof electrlc energy are arranged in series with are lamps or in serieswith other devices or other incandescent lamps.

The invention is designed to provide for two contingencies which mayarise following the rupture of the carbon of the incandescent lamp-t.6., first, abnormally-high resistance at that point of the circuit; or,second, abnor-. mally-low resistance which sometimes follows theformation of a substitute path for the current from wire to wire whenthe current travels from wire to wire in the vacuum-chamber of the lamp,as an arc in cacao.

Forthe purpose of my invention I employ a magnet or solenoid, preferablythe latter, wound with two coils, one in the main orline circuit and theother in a derived or shunt circuit, around the incandescent lamp orother translator of electric energy. The core or armature of the magnet,whenattracted, moves a contact,which closes a shunt-circuit around theincandescent lamp or other translator. The magnets coils are wound so asto oppose each others action,forming a differential magnet. A rupture ofthe filament or carbon conductor of the incandescent lamp,or generally asudden increase in the resistance of the translator of electricenergy,in whatever form it may be, causes an attraction of the core or.armature and closing of the shunting contacts, which are thereafterretained closed by the coil in the main or line circuit. A considerablefall in the resistance wi1l,as herein sh own, operate likewise.

I11 the accompanying drawings, Figure 1 shows one of the forms of anapparatus embodying my invention. Fig. 2 shows a more completearrangement. Fig. 3 is a detail view Fig. 5is

(No model.)

a modified arrangement of a very compact design with an ordinaryelectro-magnet, not axial. v

In Fig. 1 wires to b are supposed to be connected with aconstant-current line or a source of electric currents of uniform volumenearly. From a a connection is carried through the main-line coil D ofthe differential magnet A, and from it to one terminal of anincandescent lamp, L, (or such device,) as indicated. A connection isalso made, as shown at e, to one of a set of contacts at T, carried bythe core 0 of the differential magnet, which closes the contact whenattracted into the axis ofthe coil D. Coincident in axis with the mainline D is a fine-wire coil, K, oppositely wound to the main-line coil D,and connected in derived circuit with the lamp L-that is, one end to b,as shown at c, Fig. 1, the wire leading from the other terminal of saidlamp, and the other end to its first-mentioned terminal, as shown at d.The wire I) has also a connection, by the wire f. as shown, to the upperor fixed contact at T. A spring or springs, S S, are used to adjust themagnetic strcngth and support the core. A variable wire-resistance(shown at v) may be used to adjust the effect of main-line coil D, as byshunting it. The adjustment must be such that, the windings D and Kbeing opposed in direction, the core 0 will not be lifted when L is inplace, and the current normal to the line passes from a to I). Thecontacts T T will of course be open, the tendency of the main-line coilD to raise the core 0 being neutralized, so far as mechanical lift-.

ing or raising of said core is concerned, by the inverse currenttraversing K in shunt to L. \Vhen, however, L loses its conductingpoweror becomes of very high resistance-as by wasting or rupture of itscarbon-more of the current traverses the fine-wire coil K, whosemagnetic power is thereby increased, and it then exerts not only asu'liicient force to neutralize the effect of opposing coil D, but asufficient additional power to cause the core G to rise and close thecontact at T T. The current then passes from a, through the coil D, tothe core, through T, (closed,) and to I), the lamp L being thus shunted,and the contact T is now held closed by the coil D acting alone. It isadvisable to make the core 0 of split tube or wire bundle, so that itsmagnetcontact at T open.

ism may be easily reversed; and it is well,also, to have the fit of thecore to the inside of the coil or tube on which the coil is wound, so asto have a dampening or slowing effect upon the motions of the core, toprevent too sudden movements. A dash-pot mightof course be added to thisend. The closing of the contacts at T T and shunting will also occurshould the lamp-resistance fall abnormally, as by the establishment ofan arc in the vacuous space from one leg of the carbon conductor to theother in L. At such time the fine-wire coil K loses a part of itsneutralizing-power and the main-line coil D asserts its supremacy,attracts the core, and shunts the apparatus,as before, through T.

In Fig. 2 a switch, IV, is shown, by which a short-circuit connectionmay be made at will from a to b, so as to light or extinguish the lamp Lat will. The main-line coil D is arranged as before, and the fine-wirecoil K, wound around the lower end of the magnet, is located, as before,in a shunt around the lamp L. The core 0, however, instead of being hungby a spring, rests on a plate-spring, S, which just supports said core,leaving the The contact at T is preferbly assisted in closing by a smallpermanent or other magnet, M, very weak in power, placed so that whenthe core 0 rises the spring S, relieved of its weight, brings a piece ofiron, N, carried thereby, near to the magnet M, resulting in a slightattraction. This magnet helps to keep the contact T closed during a verysmall interval of time, which may be needed for the core 0 to reverseits magnetism after the fine-wire coil K has lifted it, and themain-wire coil D is to hold it up, as described in connection withFig. 1. In all other respects the same actions take place as with Fig.1.

In Fig. 3 the core 0 is shown constructed as a fairly-fitting plungerentering the bobbin E, upon which the coils D and K are wound. The upperend of the bobbin E is closed, and the core so arranged has the effectof a dash-pot, and is useful in preventing the too sudden movements ofthe parts. The core 0 is also shown almost counterbalanced by a weight,S, instead of springs, as in Figs. 1 and 2. A link, Z, connects the core0 to the contact mechanism. The link has a small slot in its lower end,in which apin on the contact-lever F has free play to a limited extent.The contact-lever bears a lower contact at T, and is pivoted so that aspring, M, may exert its force on a pin, N, in said lever on either sideof a dead-eenter, according to the throw given by the core (3 and linkZ. The slot in the link Z is of sufficient length to allow free play tothe contact-lever F in closing contact at T. Thus when the core 0 risesthe link Zlifts the lever F.

The spring M is thrown above the dead-center, when it imparts a suddenupward movement to'the outer end of the lever F, near the contact,resulting in a sudden closure at T. When the core begins to descend, itcan have no effect to open the contact at T until the upper end of theslot in Z bears on the pin in F. This allows a certain amount of freeplay to the core 0, during which time it will not affect the contact atT. Ample opportunity for reversal of magnetism, as before described, isthus secured, and during such reversal the core 0 virtually remainsattracted, inasmuch as it may fall slightly, butin doing so does notopen T.

In Fig. 4c the core 0 is made to carry the fine wire coil K in itsmovements, its weight and that of the core being balanced by a spring,S, bearing the contacts T normally open. Its operation is the same as inFig. 1, though not so perfect.

In Fig. 5 the axial magnet is replaced by an electro-magnet whose coreis wound' with the two coils D K differentially, and the armature O isarranged to be attracted and held to close the contact T when eitherwinding preponderates in effect. A spring-rctractor, S, though notnecessary, may assist in adjustment, in virtually adding to the weightofthe armature itself. A dash-pot, G, with oil or glycerine, may beemployed to check sudden or vibratory movements of the armature C. Theoperation and connections are substantially as in the preceding figures,excepting that movements of the core are replaced by those of anelectro-magnet armature.

It is to be understood that other forms of differential magnet may besubstituted for those shown, provided the form selected permits eithercoil to preponderate under the described conditions, andthus close acontact which shunts the current around the lamp.

I am aware that cut-off devices have been wound with fine and coarsewire, the fine wire being connected in derived circuit around a lamp orother resistance and the coarse wire only thrown into action upon theclosure of the contact, or, when kept in circuit, cut out by the closureof a contact upon retraction of the core or armature.

In my invention it is essential that the cutoff contact be closed byeither coil acting singly or by the prepondcrating coil when they acttogether. It is also a feature of inyinvention that that coil which isin the main circuit at all times retains the core uplifted and keeps thecontact closed, unless sufficiently opposed by the fine-wire coil K, andthat when the core has been lifted by the fine-wire coil a reversal ofmagnetism takes place in the core, due to the reverse winding of thecoarse or main-circuit coil and subsequent retention of the core in alifted state, with retention of contact by said coarse coil actingalone.

In this specification I have described my invention in connection with asystem of electric lamps; but it is evident that it may be used whereverthe same conditions occur, as in an electric motor or other translatorof electrical energy. I do not limit myself, therefore, to a cut-out forincandescent lamps; but

\Vhat I do claim is ICC 1. The combination, with an incandescent lamp,electric motor, or other translator of electric energy, of a coil in themain or leading circuit to such translator, a coil in a derived circuitof approximately constant resistance around the translator, a shuntaround the translator, and a device responding to the differentialaction of such coils and adapted to close such shunt when either coilpreponderates in power, and to keep such shunt closed thereafter by thepower of the main-line coil, as and for the purpose described.

2. In anincandescentlamp, the combination of a coil in the main orfeeding circuit, a coil in a derived circuit of approximately constantresistance around the lamp, and a core or armature or equivalentmagnetic device responding to the differential action of such coils,whereby it is adapted to close a shunting contact around the lamp wheneither coil preponderates in power, and to retain such contact closed bythe action of the coil in. the main or leading circuit, as and for thepurpose described.

3. In an incandescent lamp, the combination of a coil in a mainline orfeeding circuit, an oppositely-wound coil in a derived circuit ofapproximately constant resistance around the lamp, such coils beingsubstantially balanced in their magnetic effect upon the armature, core,or equivalent device under normal conditions of current and resistance,and which attract such armature or core and close such shunt upon thepreponderance of either coil,

.due to abnormally high or low resistance in lamp when either coilpreponderates in effect alent device, so adjusted as to be indifferentto such differential magnet under normal conditions of current andresistance, and to close a shunt around thelamp upon the preponderanceof either coil, due to abnormally high or low resistance within thelamp, as and for the purpose described.

6. In an incandescent lamp, the combination of a coil in the maincircuit of approximately constant resistance, a coil in derived circuitabout the lamp, an armature, core, or equivalent device, and a contactmechanism in shunt to the terminals of the lamp, said armature beingnearly balanced under normal conditions of current and resistance andadapted to close such contact mechanism upon a preponderance of magneticstrength in either coil and to keep such contact closed by the magneticstrength of the main coil, as and for the purpose described.

7. In an incandescent lamp, the combination of a differential magnet, acore, armature, or equivalent device, a contact mechanism, and acontact-retaining mechanism to hold such contact mechanism closed duringthe reversal of polarity of such magnet and pole, as and for the purposedescribed.

8. In an incandescent lamp, the combination of a differential magnet, acore, armature, or equivalent device, a contact mechanism which isclosed by preponderance of either coil and then held closed by theaction of a certain one of them, and a contact-retaining mechanism tohold such contact mechanism closed during reversal of polarity of themagnet and core, as and for the purpose described.

9. In an incandescent lamp, the combination of a differential magnet, acore, armature, or equivalent device, a contact mechanism controlledthereby, and means for checking the sudden movements of said core.armature, or equivalent device upon reversal of polarity of such magnetand core, and for the purpose described.

Signed at Lynn, in the county of Essex and State of llilassachusetts,this 19th day of August, A. D. 1886.

ELIHU THOMSON.

Witnesses:

J. W. GIBnoNEY, E. WILBUR Bron, J r.

